不知道大家做了HelloGallery试验没有。
兄弟本来Gallery试验早就做了,先开始是参照HelloViews文档做。貌似不行。主要问题是没有贴一个主题样式配置文件。
小抱怨一下Android SDK文档的更新不及时以及太概述,可能是Google有意要锻炼大家的学习主动性。
瞎话少叙,实例伺候。
 
Step1、布局及资源
 
main.xml
 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        >
  <TextView    
         android:layout_width="fill_parent"    
         android:layout_height="wrap_content"    
         android:text="@string/hello"
         />
  <Gallery
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/gallery">
  </Gallery>
        
</LinearLayout>
 
string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
        <string name="hello">Hello World, HiGallery!</string>
        <string name="app_name">HiGallery</string>
        <string name="gallery_text">Gallery Context button test</string>
</resources>
 
如果你的HelloGallery抱怨,请把下面配置文件补上。
attrs.xml
<?xml version="1.0" encoding="utf-8"?>

<resources>
        
        <!-- These are the attributes that we want to retrieve from the theme
                 in view/Gallery1.java
-->
        <declare-styleable name="GalleryOne">
                <attr name="android:galleryItemBackground" />
        </declare-styleable>
        
</resources>
 
Step2、Java代码
package com.penguin7.gallery;

import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.AdapterView.AdapterContextMenuInfo;

public class HiGallery extends Activity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
                
                // 引用Gallery视图
                Gallery g = (Gallery)findViewById(R.id.gallery);
                // 设定适配Gallery对象为自定义图像适配器ImageAdapter
                g.setAdapter(new ImageAdapter(this));
                
                // 新建AdapterView匿名对象设定事件监听,并使用Toast消息提示
                g.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                  @Override
                        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                                Toast.makeText(HiGallery.this, "This is number " + position, Toast.LENGTH_SHORT).show();
                        }
                });
                
                // 为Gallery对象注册背景上下文按钮
                registerForContextMenu(g);
        }

        @Override
        public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
                menu.add(R.string.gallery_text);
        }
        
        @Override
        public boolean onContextItemSelected(MenuItem item) {
                AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
                Toast.makeText(this, "Context Menu Longpress: " + info.position, Toast.LENGTH_SHORT).show();
                return true;
        }

        public class ImageAdapter extends BaseAdapter {
                int mGalleryItemBackground;
                
                public ImageAdapter(Context c) {
                        mContext = c;
                        // 获取上下文主题风格信息 定义在res/values/attrs.xml中
                        TypedArray a = obtainStyledAttributes(R.styleable.GalleryOne);
                        mGalleryItemBackground = a.getResourceId(
                                        R.styleable.GalleryOne_android_galleryItemBackground, 0);
                        a.recycle();
                }

                public int getCount() {
                        return mImageIds.length;
                }

                public Object getItem(int position) {
                        return position;
                }

                public long getItemId(int position) {
                        return position;
                }

                public View getView(int position, View convertView, ViewGroup parent) {
                        ImageView i = new ImageView(mContext);

                        i.setImageResource(mImageIds[position]);
                        i.setScaleType(ImageView.ScaleType.FIT_XY);
                        i.setLayoutParams(new Gallery.LayoutParams(136, 88));
                        
                        // The preferred Gallery item background
                        i.setBackgroundResource(mGalleryItemBackground);
                        
                        return i;
                }

                private Context mContext;

                private Integer[] mImageIds = {
                                R.drawable.gallery_photo_1,
                                R.drawable.gallery_photo_2,
                                R.drawable.gallery_photo_3,
                                R.drawable.gallery_photo_4,
                                R.drawable.gallery_photo_5,
                                R.drawable.gallery_photo_6,
                                R.drawable.gallery_photo_7,
                                R.drawable.gallery_photo_8
                };
        }

}

 
Step3、效果图